The Waiting Train Mechanism. ---------------------------- So called, because the clock 'waits' for a few seconds every half minute for an accurately timed, brief electrical impulse from a master clock. This restarts the drive to the clock hands. For the rest of the half minute the pendulum drives the clock hands normally. During the short 'wait' the drive pawl is simply lifted away from the teeth of the escape wheel by a half round or "D" shaped brass pin. The pendulum continues to swing normally but the drive to the clock hands is disconnected for a few seconds. The exact timing of these low voltage controlling impulses keeps the Waiting Train movement accurate to a few seconds per week. The 'WT' being entirely dependant on the accuracy of the controlling master clock for its own timekeeping.

When the half-round 'D' shaped pin (jutting from the side of the escape wheel) arrives at its lifting position. The masking pawl is lifted by the pin until the right angled lever is locked onto the catch. (the catch is the step in the armature of the relay electromagnet) The catch is counterbalanced to rise (when allowed to do so) by its counterweight. This ensures that the right angle lever will always be safely locked by the catch when allowed to do so. The masking pawl and right angle lever form one unit pivoted near where they are joined. Close inspection of the escape wheel reveals a higher tooth just above the D-shaped pin. This single higher tooth allows the driving pawl to remain engaged as it is itself lifted by the masking pawk. If all the teeth were the same height the driving pawl would miss the last tooth as it was (itself) lifted out of the way by the D-shaped pin.

The masking pawl lifts the driving pawl away from the teeth of the escape wheel.

A closer view (below) of the right angled lever safely locked onto the stepped catch of the relay armature of the relay electromagnet. The masking pawl is firmly fixed to the right angled lever and pivots with it. When the right angled lever is locked by the catch the driving pawl simply slides on top of the masking pawl. So is unable to pull the teeth of the escape wheel round.

The relay electromagnet waits for a short electric impulse from an accurate master clock.

An accurately-timed low voltage impulse arrives from the seperate "Pulsynetic" electric master clock every 30 seconds. This causes the stepped armature catch to be drawn quickly downwards by the relay electromagnet. The previously-locked right angle lever is now free to fall to its normal position. The attached masking pawl also drops allowing the driving pawl back into contact with the teeth of the escape wheel. The driving pawl then pulls the next tooth round on the escape wheel and so the cycle continues for another 27 seconds.

Closer view of the relay electromagnet. (locking catch in locked position)

The escape wheel is stopped from rotating backwards by the back stop click. Which is a steel arm (the click) resting in the escape wheel teeth. A brass counterweight keeps the click safely in contact with the escape wheel teeth at all times. The click lifts and falls over each tooth of the escape wheel as it is drawn round by the driving pawl. The click and its counterweight are pivoted in a large brass hub.

The brass hub is partially hidden here behind the right angled lever.

The lacquered brass horizontal driving pawl draws the escape wheel round one tooth at a time on every swing of the pendulum to the right. On the return swing the driving pawl hops over the next tooth that it will draw round on the next swing to the right. All these parts are robustly built to ensure strength and long-term reliabilty. The driving pawl is the vital connection between the heavy pendulum and the escape wheel. Which then drives the clock hands via the worm & wormwheel and the bevel gears. The wormwheel acts as a constant safety (locking) device on the drive to the hands of the outside dials. The wormwheel cannot possibly rotate except when driven by its worm. Any unusual imbalance in the clock hands due to encrusted ice must be safely resisted by the wormwheel & its worm alone. Clock hands are always carefully counterbalanced to avoid irregular loads on the movement. But the quantity of ice is always unpredictable.

The driving pawl sliding on top of the masking pawl during the short waiting period.